﻿Imports System.IO
Imports System.Text.Encoding
Imports System.Security.Cryptography

Friend Class TrippleDesEncryption

    Private TripleDes As TripleDESCryptoServiceProvider = Nothing
    Private Key As String = "LlÔXTèLlÔXTè"

    Sub New()
        'Initialize the crypto provider.
        Me.TripleDes = New TripleDESCryptoServiceProvider
        TripleDes.Key = TruncateHash(Me.Key, TripleDes.KeySize \ 8)
        TripleDes.IV = TruncateHash("", TripleDes.BlockSize \ 8)
    End Sub

    Private Function TruncateHash(ByVal key As String, ByVal length As Integer) As Byte()

        Dim sha1 As New SHA1CryptoServiceProvider

        ' Hash the key.
        Dim keyBytes() As Byte = System.Text.Encoding.Unicode.GetBytes(key)
        Dim hash() As Byte = sha1.ComputeHash(keyBytes)

        ' Truncate or pad the hash.
        ReDim Preserve hash(length - 1)
        Return hash

    End Function

    Public Function EncryptData(ByVal plaintext As String) As String

        ' Convert the plaintext string to a byte array.
        Dim plaintextBytes() As Byte =
            System.Text.Encoding.Unicode.GetBytes(plaintext)

        ' Create the stream.
        Dim ms As New System.IO.MemoryStream
        ' Create the encoder to write to the stream.
        Dim encStream As New CryptoStream(ms,
            TripleDes.CreateEncryptor(),
            System.Security.Cryptography.CryptoStreamMode.Write)

        ' Use the crypto stream to write the byte array to the stream.
        encStream.Write(plaintextBytes, 0, plaintextBytes.Length)
        encStream.FlushFinalBlock()

        ' Convert the encrypted stream to a printable string.
        Return System.Convert.ToBase64String(ms.ToArray)
    End Function

    Public Function EncryptData(ByVal plaintextBytes() As Byte) As String

        '' Convert the plaintext string to a byte array.
        'Dim plaintextBytes() As Byte =
        '    System.Text.Encoding.Unicode.GetBytes(plaintext)

        ' Create the stream.
        Dim ms As New System.IO.MemoryStream
        ' Create the encoder to write to the stream.
        Dim encStream As New CryptoStream(ms,
            TripleDes.CreateEncryptor(),
            System.Security.Cryptography.CryptoStreamMode.Write)

        ' Use the crypto stream to write the byte array to the stream.
        encStream.Write(plaintextBytes, 0, plaintextBytes.Length)
        encStream.FlushFinalBlock()

        ' Convert the encrypted stream to a printable string.
        Return System.Convert.ToBase64String(ms.ToArray)
    End Function

    Public Function DecryptData(ByVal encryptedtext As String) As String

        ' Convert the encrypted text string to a byte array.
        Dim encryptedBytes() As Byte = System.Convert.FromBase64String(encryptedtext)

        ' Create the stream.
        Dim ms As New System.IO.MemoryStream
        ' Create the decoder to write to the stream.
        Dim decStream As New CryptoStream(ms,
            TripleDes.CreateDecryptor(),
            System.Security.Cryptography.CryptoStreamMode.Write)

        ' Use the crypto stream to write the byte array to the stream.
        decStream.Write(encryptedBytes, 0, encryptedBytes.Length)
        decStream.FlushFinalBlock()

        ' Convert the plaintext stream to a string.
        Return System.Text.Encoding.Unicode.GetString(ms.ToArray)
    End Function

    Public Function DecryptData_Bytes(ByVal encryptedtext As String) As Byte()

        ' Convert the encrypted text string to a byte array.
        Dim encryptedBytes() As Byte = System.Convert.FromBase64String(encryptedtext)

        ' Create the stream.
        Dim ms As New System.IO.MemoryStream
        ' Create the decoder to write to the stream.
        Dim decStream As New CryptoStream(ms,
            TripleDes.CreateDecryptor(),
            System.Security.Cryptography.CryptoStreamMode.Write)

        ' Use the crypto stream to write the byte array to the stream.
        decStream.Write(encryptedBytes, 0, encryptedBytes.Length)
        decStream.FlushFinalBlock()

        ' Convert the plaintext stream to a string.
        Return ms.ToArray
    End Function

End Class
